Q I started taking 10,000 IU of vitamin D a day. Six months later, I suddenly developed severe constipation. Was the constipation caused by the large dose of vitamin D?

A Vitamin D is a superstar among vitamins these days. It has become clear that low vitamin D levels are common and that the consequences can be serious. Too little vitamin D has been linked to a higher risk for conditions such as arthritis, cancer, osteoporosis, diabetes and even heart disease and stroke (American Journal of Epidemiology, Oct. 15, 2009).

It's no wonder that many people have decided to take more vitamin D. Many experts agree that the RDA of 400 IU daily is too low. But excess vitamin D, a fat-soluble vitamin, can be toxic. Constipation is one possible symptom of too much vitamin D. Other side effects may include digestive upset and weakness.

Q I have a curious question. Whenever I take a Tums Dual Action tablet for heartburn, I can't go to sleep. It keeps me awake all night.

I've tried taking half a tablet and taking it earlier, but it still keeps me awake. Why could this be? Is it the famotidine? I can take the regular Tums just fine.

A Tums Dual Action contains calcium carbonate, magnesium hydroxide and famotidine. Famotidine is an acid reducer that doesn't usually cause insomnia. Nevertheless, this symptom has been reported (infrequently) as a side effect in some clinical trials. You may be one of those rare individuals who are affected. You might want to stick with regular Tums (calcium carbonate) or find a different way to treat your heartburn.

Q Please tell your readers that taking moderate amounts of a magnesium supplement can alleviate depression. I have personally had good results taking magnesium aspartate, oxide or citrate salts, at a dose of at least 400 mg of magnesium a day.

Last year, my girlfriend had a friend who was suffering from major depression and had to go on disability from her teaching job as a result. She was under medical care, but still having a lot of difficulties. After we gave her a big bottle of magnesium oxide tablets, she started to recover. She's doing much better now and is back to teaching and going out and doing things.

I can't think of another treatment that is so cheap, simple and safe.

A There is science to back you up. An epidemiological study found a link between low magnesium levels and symptoms of depression in Norway (Australian and New Zealand Journal of Psychiatry, January 2009). An experiment in Mexico found that magnesium worked as well as the antidepressant drug imipramine to relieve depression in elderly people with type 2 diabetes (Magnesium Research, December 2008).

A review suggests that inadequate magnesium reduces the amount of the neurochemical serotonin in the brain (Medical Hypotheses, April 2010). The authors believe that magnesium treatment might help many people with depression, including those like your acquaintance with treatment-resistant depression.

At too high a dose, magnesium causes diarrhea. People with kidney disease must avoid supplements of this mineral.

In their column, Joe and Teresa Graedon answer letters from readers. Send questions to them via peoplespharmacy.com.


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